1. Field of the Invention:
This invention relates to a gland packing box composed in a shaft seal part of a hydraulic machine, and more particularly to a structure of a gland packing box suppressing the power loss as much as possible while enhancing the lubricating function and cooling function of the seal part.
2. Description of the Prior Art:
As a general conventional structure of a gland packing, the construction as shown in FIG. 20 is known. In the drawing, numeral 100 is a packing box formed at an end of, for example, a pump casing, 101 is a neck bushing, 103A, 103B are gland packings, 104 is a packing gland, and 105 is a rotary shaft, in which the gland packings 103A, 103B are pressed in the axial direction with a specified tightening pressure by the neck brshing 101 inserted deep in the packing box 100 and the packing gland 104 with the end part set in the opening of packing box 100, thereby maintaining a sealing for the rotary shaft 105.
The structure of the gland packing box is so designed as to prevent abnormal wear of the rotary shaft 105 or seizure of seal part 106 due to dry operation, by allowing fluid from the seal part 106 between the outside of the rotary shaft 105 and the inside of the gland packings 103A, 103B to, and by providing this escaping fluid with a lubricating function and a cooling function.
In the conventional structure of a packing box stated above, however, the gland packing fitting faces 101A, 104A abutting against the gland packings 103A, 103B of the neck bishing 101 and packing gland 104 respectively, are formed in a shape to be perpendicular and uniform to the axial line of the rotary shaft 105, and the gland packing 103A, 103B are held by these packing fitting faces 101A, 104A, so that the axial ends of the gland packings 103A, 103B naturally cross perpendicularly and uniformly to the axial line of the rotary shaft 105.
Therefore, a tiny annular gap 107 formed between the inside of the neck bishing 101 and the outside of the rotary shaft 105 only corresponds to the axial end of the gland packing 103A, and does not overlap with the inside of the gland packing 103A in the circumferential direction.
Accordingly, the escaping fluid functioning as lubricant and coolant is sent into the seal part 106 only through the inner end in the axial direction of the tiny annular gap 107. However, since it is designed to press the inside of the gland packings 103A, 103B to the outside of the rotary shaft 105 and keep a favorable sealing performance by tightening the packing gland 104 in the direction of the neck bushing 101 with a specified tightening pressure, the inside of the gland packings 103A, 103B and the outside of the rotary shaft 105 forming the seal part 106 is in a tight contact state, and it is practically difficult to send the escaping fluid only by the fluid pressure in the casing into such a seal part 106, and the leak flow is diminutively limited, and the lubricating function and cooling function cannot be exhibited effectively.
Still more, if the tightening pressure of the packing gland 104 is excessive, or when the inner peripheral edge of the gland packing 103 projects into the tiny annular gap 107 due to the effect of internal stress of the gland packings 103A, 103B, or the like, this projecting part locally becomes high in density, and the leak flow into the seal part 106 is extremely limited, and the lubricating function and cooling function are lowered, which may lead to problems such as abnormal wear of the rotary shaft, seizure of the seal part due to dry operation, and other troubles.
Such problems also occur in the part of a tiny annular gap 108 formed between the inside of packing gland 104 and the outside of rotary shaft 105 in FIG. 20.
Hence, by forming a cooling jacket 109 on the peripheral wall of the packing box 100, for example, circulating cooling water and forming a passage 110 communicating with the tiny annular gap 108 in the packing gland 104, and introducing through this passage 110, for example, cooling water into the tiny annular gap 108 the cooling effect is. enhanced In spite of these effects, however, since the cooling jacket 109 is only to cool the gland packings 103A, 103B directly, much of a cooling effect on the seal part 106 is not expected, and the lubricating effect is not expected at all.
Incidentally, if the cooling water is led into the tiny annular gap 108 through the passage 110, only the slight portion corresponding to the tiny annular gap 108 or the projecting portion of the gland packing 103B is directly cooled by this cooling water, and the cooling effect and lubricating effect on the seal part 106 cannot be expected as in the case of the cooling jacket 109 above.